Telephone system



E.- R. LUNDlUS.

TELEPHONE SYSTEM.

APPLICATIQN FILED JAN. 4, 191a.

Patented Jan. 27, 1920.

UNITED STATES PATENT OFFICE.

ERIC R. LUNDIUS, OF BROOKLYN, NEW' YORK, ASSIGNOR T0 WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE SYSTEM.

means have been provided for connecting a source of signaling current to the line when at its mlnimum strength and then gradually increasing the current to a maximum strength, for causing the receiver connected with the line to produce a warning signal which gradually increases from a minimum to a maximum intensity. It is the object of the present invention to provide in asystem of this character improved and simplified means for controlling the connection of the source of signaling current to the telephone line, whereby the chances for producing disagreeable and eiitremely intensive warning signals in a subscribers car are reduced to a minimum.

For a more complete understanding of the invention reference should be 'had to the following description considered in connection with the accompanying drawing illus trating one embodiment thereof.

There is shown in the drawing a telephone line A extending to and terminating at a central office at which is located a connecting circuit B. This connecting circuit B maybe employed upon connection thereof with the telephone line to connect a source of signaling current with theline for causing the receiver at the station thereof when operatively connected with the line to produce a warning signal. Means for gradually varying the strength of the signaling current. connected to the line comprises an induction coil 5 with whose primary wind ing may be connected a source of intermittent current derived from a battery and an interrupter 6. The secondary winding of the induction coil 5 is divided into sections the tap leads from which are successively connected with conductive segments of a Specification of Letters-Patent. Patented Ja 27, 192() Application filed January 4, 1918. Serial No. 210,253.

of secondary segments in circuit is gradu-- ally increased from a minimum to a maximum. This induction coil 5, having a di-v vided secondary with which is associated the rotating brush 8, and the stationary ring 7 of conducting segments, comprises cont-rolling means for gradually varying the strength of the signaling current connected to the line.

With this brief description of the apparatus shown in the drawing, it is thought that the invention may be'best understood from a description of the operation of the system disclosed. If the receiver at station A re mains removed from its switchhook at the termination of the conversation and after the withdrawal of the usual central office link circuit from its answering or multiple jack, line relay 10 will ,be operated and line lamp 11 lighted. An operator, upon connecting with this line, does not find a calling subscriber thereon, and therefore knows that the receiver has been left off the switchhook. Under such circumstances and in order that the subscriber may be signaled to restore the receiver to the switchhook, the operator disconnects from the line, and plug 15 of the connecting circuit B is then inserted into jack 16, whereupon relay 17 and cut-ofi relay 12 are operated. A connecting key 18 of the locking type is then actuated. Supervisory relay 19 is also operated upon the connection of the plug 15 with the jack 16 and in operating causes the energization of relay 20 over a circuit from battery through the contact of supervisory relay 19, the winding of relay 20, resistance 21, and the contact of relay'17 to ground. The winding of relay 19 and 20 having previously operated, relay 23 is energized .over a circuit from battery through resistance 24, the winding of relay 23, conductive segment 25 of the ring 7, the

brush 8, the upper contact of the key 18, and a winding of repeating coil 26 to ground. Relay 23 upon being energized connects battery and the interrupter 6 in circuit with the primary winding of the induction coil 5, and establishes a locking circuit for itself from battery through the resistance 24, the winding and the upper contact of relay 23, the lower contact of the key 18, and the contact of relay 17 to ground. Relay 23 thereafter remains energized independent of the position of the brush 8 with respect to the conductive seg ment 25 of the ring 7. The secondary of the induction coil 5 is connected with the line through the upper and'middle contacts of the actuated key 18. Intermittent current flowing through the primary winding of the induction coil 5 induces into the secondary winding an alternatingcurrent, the effective strength of which is gradually increased due to the rotation of the brush 8, which gradually increases, from a minimum to a maximum, the number of the secondary sections connected in the circuit. The signaling current so connected with the line causes the receiver at the station A to produce a warning signal, which gradually varies from a minimum to a maximum intensity. It is to be observed that if the key 18 is actuated at the time the plug 15 is inserted into the .jack 16' the energization of relay 23 serves to connect the source of signaling current with the telephone line. Since the closed primary circuit can only be established when the brush 8 is on the conducting segment 25 and no sections of the secondary are in circuit, the warning signal produced by a receiver always begins at its minimum intensity. In

this manner loud and disagreeable clicks in the ear of a subscriber are prevented should the subscriber have the receiver to his ear at the time the warning signal starts.

The subscriber at station A having heard the warning signal restores the receiver to the switchhook, thereby causing the de'nergization of the supervisory relay 19, which releases its armature, removing the shunt from the lamp 22 which thereupon lights to furnish a signal to the operator. thereupon becomes de'c'n'ergized and releases its armature, thereby short-ci-rcuiting the winding of relay 23 and causing the release thereof, which disconnects the source of intermittent current from the primary winding of the induction coil 5. As long as the receiver remains on its switchhook the relay 20 remains deenergized, maintaining the short circuit about the relay 23; hence this relay 23 can not be energized as long as the receiver remains on its switchhook. Therefore the signaling current'can not be connected with the line. After once becoming deenergized, relay 23 can not be energized again, even if the receiver is off its switch- Relay 2O brush 8 has again engaged the conducting segment 25. In other words the signaling current isdisconnected from the line immediately upon the opening of the line at the subscribers station and there is no possibility that the receiver will immediately thereafter produce a warning signal upon the closure of the telephone line. Therefore adequate protection is aiforded subscribers who must be signaled in this manner when leaving the receiver removed from its switchhook.

What is claimed is:

1. A telephone system comprising a telephone line, a receiver connected therewith, a connecting circuit, a relay in the connecting circuit responsive to the connection thereof with the telephone line, a source of signaling current, aswitching device for controlling the strength of the signaling current. asecond relay whose energization is controlled by the response of the first relay for connecting the signaling current with the telephone line for causing the receiver to produce a warning signal, and a third relay controlled over the telephone line and deenergized by the opening thereof to cause the deenergization of the second relay.

2. A telephonesystem comprising a tele phone line, a receiver connected therewith, a connecting circuit, a relay in the connecting circuit responsive to the connection thereof with the telephone line, a source of signaling current, a switching device for controlling the strength of the signaling current, a second relay whose energization is controlled by the response of the first relay for connecting the signaling current with the telephone line for musing the receiver to produce a warning signal. and a third relay controlled over the telephone line and deenergized by the opening thereof for discoir necting the signaling current from the line.

3. A telephone system comprising a telephone linc. a receiver connected therewith. a connecting circuit. a relay in the connecting circuit responsive to the connection thereof with the telephone line. a source of signaling current, a switching device for c mtrolling the strength of the signaling current. a second relay whose energization is controlled by the response of the first relay for connecting the signaling current phone line, a receiver with the telephone line for causing the receiver to produce a warning signal, a third relay controlled over the telephone line and decnergized by the opening thereof, and a short circuit for the second relaycontrolled by the deenergizat-ion of the third relay.

A telephone system comprising a teleconnected therewith, a connecting circuit, a relav in the connecting circuit energized over the telephone line when connection is made therewith, a source of signaling current, a switching device for controlling the strength of the signaling current, a second relay for connecting the source of signaling current with the telephone line for causing the receiver to pro-- duce a warning signal, and an energizing circuit for the second relay controlled by the control switching device and the first relay and established when the control switching device is in a particular position and when the first relay is energized.

5. A telephone system comprising a telephone line, a receiver connected therewith, a connecting circuit, a relay in the connecting circuit energized over the telephone line when connection is made therewith, a source of signaling current, a switching device for controlling the strength of the signaling current, a second relay for connectlng the source of signaling current with the telephone line for causingpthe receiver to produce a warning signal, an energizing circuit for the second relay cont-rolled by the control switching device and the first relay and established when the control switching device is in a particular position and when the first relay'is energized, and a locking circuit for the second relay established by the energization thereof for rendering this relay independent of the control switching device.

6. A telephone system comprising a telephone line, a receiver connected therewith, a connecting circuit, a relay inthe connecting circuit energized over the telephone line when connection is made therewith. a source of signaling current, a switching device for controlling the strength of the signaling current, a second relay for connecting the source of signalingcurrcnt with the telephone line for causing the receiver to produce a warning signal, an energizing circuit for the second relay controlled by the control switching device and the first relay and establishcd when the control switching device is in a particular position and when the first relay is energized, and means for docncrgizing the second relay controlled by the dcenergization of the first relay.

7. A telephone system comprising a telephone line, a receiver connected therewith. a connecting circuit. a relay in the connccting circuit energized over the telephone line when connection is madc therewith. a source oi signaling current, a switching device for telephone line,

v a connecting circuit, a relay in the connect-- ing circuit energized over the telephone line when connection is made therewith, a sourceof signaling current, a switching device for controlling the strength of the signaling current, a second relay for connecting. the source of signaling current with the telephone line for causing the receiver to produce a warning signal, an energizing circuit for the second relay controlled by the control switching device and the first relay and established when the control switching device is in a particular position and when the first relay is energized, a locking circuit for the second relay established upon the energization thereof for rendering this relay independent of the control switching device, and a circuit controlled by the deenergization of the first relay for rendering the lock ing circuit ineffective and for preventing the reenergization of the second relay.

9. Atelephone system comprising a telephone line, a receiver connected therewith, a connecting circuit, a relay responsive to the connection thereof with the telephone line. a second relay energized over the connected a source of signaling current, a switching device for controlling the strength of thesignaling current, a third relay for connecting the source otsignaling current with the telephone line for causing the receiver to produce a warning signal, and an energizing circuit for the third relay controlled by the second relay and established by the response of the first relay when the control switching device is in a particular position and when the second relay is energized.

10. A telephone system comprising a telephone line, a receiver connected therewith. a connecting circuit. a relay responsive to the connection thereof with the telephone line, a second relay energized over the connected telephone line. a source of signaling current. a switching device for controlling the strength of the signaling current. a third relay for connecting the source of signaling current with the telephone line for causing the receiver to producc a warning signal. an energizing circuit for the third relay controlled by the second relay and established by the'response of the first relay when the control switching device is in a particular position and'when the second relay is energized, and a, locking circuit for the third relay controlled by the energization thereof for rendering this relay independent of the control switching device and including a contact of the first relay.

11. A telephone system comprising a telephone line, a receiver connected therewith, a connecting circuit, a relay responsive to the connection thereof with the telephone line, a second relay energized over the connected telephone line, a source of signaling current, a switching device for controlling the strength of the signaling current With the telephone line for causing the receiver to produce a Warning signal, a third relay,

an energizing circuit for the third relay controlled by the second relay and established by the response of the when the control switching device is in a particular position and when the second relay is energized, a locking circuit for the third relay controlled by the energization thereof for rendering this relay indepencent of the control switching device and including a contact of the first relay, and a circuit controlled by the denergization of the second relay for rendering the locking circuit inelfective and for preventing the re-' energization of the third relay.

In witness whereof, I hereunto subscribe my name this 29th day of 1917.

ERIC R. LUNDIUS.

first relay- December A. 1)., 

